Gauging device



Oct. 30, 1945. Q J. H. STRAW 2,387,814

GAUGING DEVICE Filed Sept. 9, 1943 -9 -1. INVENTOR.

W H Jaw)- ATTORNEY.

Patented Oct. 30, 1945 Jesse H. straw, Dayto Ohio, I as'signor a T e Sheflield Corporation, Dayton, Ohio, a corpora! tion of Ohio Application September 9, 1943,:seria1 N0. 501 ,S598

1 Claim. ores-gut) This invention relates to thread gauges.

One object of the invention is the provision of a thread gauge which is simple in construction and cheaply and accurately made and conveniently used to obtain a measurement or check on the thread crests of a part to be gauged.

Another object is the provision of a thread gaugemore particularly for checkin a tapered thread and providing an indication of the accuracy of the thread crests of a part to be checked;

Other objects and advantages of the invention will be apparent from the following description, the appended claim,and the accompanying drawing; in which:

Fig. 1 is an elevational view of a thread gauge embodying the present invention, shown in its relation to a part to be checked which has been indicated in section;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is an enlarged sectional view showing the cooperation between the thread gauge and the part to be gauged; and

Fig. 4 is a view of a portion of Fig. 1, illustrating the movable support of one of the gauging arms.

' In the present illustrative disclosure, the invention is shown as incorporated in a thread gauge for gauging pipe or tapered threads, but it will be understood that the present disclosure is by way of illustration only and that the invention is susceptible of other embodiments than those which have been illustrated. Referring more particularly to the drawing, in which the same reference numerals have been used to designate like parts in the several views, designates the handle, II the shank, and I2 the threaded body member of a thread gauge shown in Figs. 1 to 3 as adapted for gauging or checking internal tapered threads of parts to be checked, one of which is illustrated at I3 in the form of a tapered thread ring having threads I 4. The threads 5 on the thread plug are adapted to be screwed in the ring until continued movement is prevented. and since the plug is of accurate size and length, the working portions of the threads on the ring are gauged by noting the extent to which the larger end of the plug projects from the ring. A notch l6 at the end of the threaded portion of the plug facilitates observing the extent to which the plug screws into the ring by noting the relationship between the bottom of the notch and the end of the ring. The notch is of such depth that if the bottom of the notch is flush with or lies within the end of the workpiece it shows the threads on the workpiece are of sufficiently large diameter.

The plug is provided with passages or g'rooves I8, extending radially inwardly to a wall "portion. |9 or the plug'and'interruptin'g theannularcoxF: tinuity of the: threads :of the plug. Asasshownz there are two of these,passagesfarrangedat.op-

posite.;sides of the plug, the two wallcportions? l9 extending parallel'to the aXis-of-the .p'1ug..

.The two passages 8-recei've two wedges-or" arms 20 and 30 which extend from and are carried by a collar 2| slidably mounted on rthe shank 2|! is rigid with collar 2|. the'collar for relative longitudinal-movementas will'be further described." Each arm 2,0,".3llhas an inner "surface 22' slidable along its respective wall portion l9, and a straight conically curved outer gauging surface 23 which is brought up against the crests of the threads on the ring or part to be checked as the collar 2| carrying the arms 20, 30 is moved to the right as viewed in Fig. 1 after screwing the plug into the ring. The outer gauging surface 23 of an arm 20, 30 has a conical curvature corresponding to the conical surface defined by the crests of the ring to be checked if the ring is of exact size, and since the gauging surface 23 is inclined with respect to the opposing surface 22, in accordance with the taper angle of the threads, the extent to which the arm 20 moves into the plug before being stopped by engagement of the surface 23 with the thread crests, provides an indication of the accuracy or diameter of the crest portions of the threads on the part checked.

The ring 2| and the shank II are provided with cooperating means to show the position of the ring and arm 20. As shown, the shank II is provided with two notches 25 and 26, which may be observed with relation to an end of the ring 2| to show whether the thread crests of the part checked fall within the required tolerance limits. Thus the end 21 of the ring should be between the two notches 25 and 26 for the thread to pass inspection, and if the side 21 of the ring is to the left of the notch 25, it shows that the crests of the threads on the ring are not cut back far enough. On the other hand, if the side 21 of the ring is to the right of the notch 26, the arm 20 has entered the ring to a greater extent than it would if the thread auged were of a desired size, thus indicating that the thread crests of the part to be checked are too large in diameter.

The arm 30 has some freedom of movement with respect to the collar 2|, in a direction parallel to the axis of the workpiece. With this arrangement, individual measurements are obtained at the opposite sides of the thread ring,

with respect to the axis of the workpiece, and it is possible to determine to a high degree of accuracy whether or not the angle defined by the thread crests is uniform throughout the length of the threaded portion of the ring. The arm 30 extends into a radially extending groove, preferably of rectangular form, in the collar 2|, and fits in the groove with a running fit so that it is held against any movement except an axial movement. The portion of the arm 30 which is within the collar is notched as indicated at 5| to provide a tongue portion 52 which is held against a pin 53, fixed in the collar, by means of a spring 54 bearing at one end against the.

pin and at the other end against a shoulder on the arm 30, as will be apparent from Fig. 4. The spring thus tends to hold the arm 30 towards the right with respect to the collar and in a limiting position in which the pin 53 prevents further movement. In this position an indicator "20- touches the thread crests, and as the move-.

ment of the collar 2| continues, to'bring the "outer side of'thearm'ZU'againstthe threads, the spring 54' is compressed and the arm 30 then projects slightly'beyond the side of the collar as shown in Fig. 4'. If the arm 30 projects too far it will bring an 'ofiset 'end'surface 56 into view and thus show that the cone definedby the thread crests is-not exact-ly centeredwith respect to the working portions of the tapered threads. And if only one end of the tapered plug is actually in full engagement with the threads of the ring and some slight angular displacement of the axis of the plug can take place with respect to the axis of the thread ring, the axial movement of the arm 30 with respect to the collar, which results, can be readily observed.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus,

and that changes may be made therein without departing from the scope of the invention which i defined inthe appended claim.

What is claimedis:

A gauge comprising a shank and a tapered threaded member on said shank adapted for threaded engagement with a tapered threaded ring, said member having opposed passages interrupting the annular continuity of the threads, a collar slidably mounted on said shank for axial movement thereonand having a pair of opposed wedge arms longitudinally m'oveable in said-passages and each provided with a straight surface engageable with the crests of the threads on the ring, said collar providing a rigid support 'for one of said arms and having means supporting the other of said armsfor relative axial movement; said shank and collar having cooperating portions showing oversize and undersiz'e conditions of the crests of the threads of thejring." 

